In a paint booth, the general object is to apply as much of the paint as possible to the articles being painted and minimize overspray. However, there is always a certain amount of overspray even with electrostatic paint sprayers. Generally the overspray is collected by forcing air through the paint spray booth. This causes the overspray to be entrained in the stream of forced air.
The air is passed through some type of water collector, such as a water curtain, which traps particles of paint carried by the air. This prevents the paint particles from being discharged into the atmosphere. Unfortunately, once the paint particles are trapped in a body of water held in a collection basin or tank, they must be removed.
Even though the paint particles are suspended in water, they still tend to be tacky. If untreated, they will form as a sludge and attach to the walls and base of the holding tank. When sufficient amounts are built up, they must be cleaned. Cleaning the tank can be very expensive and time consuming.
To overcome this, the paint particles are treated with various compositions and agents to in effect detackify the particles preventing them from sticking together to form a sludge. This also prevents them from sticking to the walls of the holding tank. These compositions and mixtures are all generally added to the water used to trap and hold the paint particles.
As an example, Mauceri U.S. Pat. No. 4,067,806 describes a cationic terpolymer of dialkyldimethyl ammonium halide, N-vinyl-2-pyrolidone acrylamide and the salt of an amphoteric metal as a paint detackification product.
Forney U.S. Pat. No. 3,861,887 discloses a blend of polycationic water dispersible polymer and a water dispersible salt of an amphoteric metal such as zinc chloride, iron chloride, lanthinum chloride or aluminum chloride.
Leitz U.S. Pat. No. 4,629,572 discloses the use of condensation resins of aldehyde and nitrogeneous compounds such as urea, melamine, thiourea, quanidine, dicyanadiamide, substituted melamine and others in combination with clay. Many other patents disclose the use of clay itself or clay in combination with other polymers as a detackification agent for paint spray booths.
Any system that employs clay presents an inherent disadvantage since the clay itself significantly increases the amount of waste material that must be discarded. Since the paint material must be treated as a hazardous waste, it is expensive to dispose. Any system that employs clay significantly increases this cost.
Other patents which disclose various treatment compositions which rely on clay, multivalent metal compositions and polymers include Mizuno U.S. Pat. No. 4,656,059, Renner U.S. Pat. No. 3,716,483, Harpel U.S. Pat. No. 4,504,395, Sellet U.S. Pat. No. 3,498,913, Gabel U.S. Pat. No. 4,055,495, and Arnold U.S. Pat. No. 3,515,575.
Generally, in addition to waste problems, many of these polymeric compositions are ineffective and particularly are not effective over a wide range of paint compositions. Further, with various compositions, there is a significant cost due to the concentration of the polymer required.